Abstract

Optical Burst Switching (OBS) has been proposed as a future high-speed switching technology for Internet Protocol (IP) networks that may be able to efficiently utilize extremely high capacity links without the need for optical-electronic (O/E) conversions at intermediate nodes. Among its benefits of supporting statistical multiplexing at a rational granularity, OBS still gives poor performance in terms of burst drop probability. In an Optical Burst Switched network, the existence of highly congested links could lead to unacceptable performance for the entire network, causing Quality of Service (QoS) degradation to flows inserted into the network. In this paper we propose a Multi-Spanning Tree architecture that improves QoS management by increasing the efficiency in the wavelength assignment process. The new protocol uses wavelength spanning trees on demand depending on the QoS constraints demanded by inserted traffics. Moreover, the protocol avoids burst overlapping on each edge of the spanning trees, while at the same time, permitting the reutilization of lambda assignments between nodes contained in the same branch. Therefore, the protocol allows traffic aggregation from many nodes into a single branch, improving efficiency and link utilization. We take a traffic engineering approach to branch selection with the objective of balancing the traffic across the network links to reduce congestion and to improve overall performance. In this paper, the architecture, the design of the protocol and some simulation results are presented. Peer Reviewed

Abstract

hieving energy efficiency has recently become an essential aim of networking research due to the ever increasing power consumption and CO2 emissions generated by large data networks. For this problem, the emerging paradigm of Software-Defined Networks (SDN) can be seen as an attractive solution. In these networks an energy-aware routing model could be easily implemented leveraging the control and data plane separation. This paper addresses the problem of optimizing the power consumption in SDN using an energy-aware traffic engineering approach that minimizes the number of links that can be used to satisfy a given traffic demand. Different from previous works, we focus on optimizing energy consumption in OpenFlow networks with in-band control traffic. Our approach also considers performance constraints that are crucial in the correct operation of SDN, such as bounded delay for the control plane traffic and load balance between controllers. First, we present a complete formulation of the optimization problem involving the routing requirements for control and data plane communications. To reduce the time complexity of our model in large-scale topologies we derive a heuristic algorithm. Significant values of energy saving (up to 60%) are reached in the simulations using real topologies and demands data. Peer Reviewed